Dust polarized emission observations of NGC 6334: BISTRO reveals the details of the complex but organized magnetic field structure of the high-mass star-forming hub-filament network
Journal article, 2021
Context.
Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation.
Methods.
We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-The-sky B-field angle (χB_POS) toward the whole region, along the 10 pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and χBPOS along the ridge crest and compared them with the results obtained from simulated filaments.
Results.
The observations span 3 orders of magnitude in Stokes I and PI and 2 orders of magnitude in PF (from 0.2 to 20%). A large scatter in PI and PF is observed for a given value of I. Our analyses show a complex B-field structure when observed over the whole region ( 10 pc); however, at smaller scales (1 pc), χBPOS varies coherently along the crests of the filament network. The observed power spectrum of χBPOS can be well represented with a power law function with a slope of-1.33 ± 0.23, which is 20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, χBPOS rotates frombeing mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (NH2 â 1023 cm-2) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure.
Conclusions.
These observational results reveal for the first time the characteristics of the small-scale (down to 0.1 pc) B-field structure of a 10 pc-long hub-filament system. Our analyses show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.
Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation.
Methods.
We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-The-sky B-field angle (χB_POS) toward the whole region, along the 10 pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and χBPOS along the ridge crest and compared them with the results obtained from simulated filaments.
Results.
The observations span 3 orders of magnitude in Stokes I and PI and 2 orders of magnitude in PF (from 0.2 to 20%). A large scatter in PI and PF is observed for a given value of I. Our analyses show a complex B-field structure when observed over the whole region ( 10 pc); however, at smaller scales (1 pc), χBPOS varies coherently along the crests of the filament network. The observed power spectrum of χBPOS can be well represented with a power law function with a slope of-1.33 ± 0.23, which is 20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, χBPOS rotates frombeing mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (NH2 â 1023 cm-2) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure.
Conclusions.
These observational results reveal for the first time the characteristics of the small-scale (down to 0.1 pc) B-field structure of a 10 pc-long hub-filament system. Our analyses show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.
Submillimeter: ISM
ISM: structure
Polarization
ISM: clouds
ISM: magnetic fields
Stars: formation
Author
Doris Arzoumanian
University of Porto
Ray S. Furuya
Tokushima University
Tetsuo Hasegawa
National Astronomical Observatory of Japan
M. Tahani
National Research Council Canada
S. I. Sadavoy
Queen's University
Charles L. H. Hull
National Astronomical Observatory of Japan
D. Johnstone
National Research Council Canada
Patrick M. Koch
Academia Sinica
Shu-Ichiro Inutsuka
Nagoya University
Yasuo Doi
University of Tokyo
Thiem Hoang
Korea Astronomy and Space Science Institute
Takashi Onaka
Meisei University
University of Tokyo
Kazunari Iwasaki
National Astronomical Observatory of Japan
Yoshito Shimajiri
National Astronomical Observatory of Japan
Tsuyoshi Inoue
Nagoya University
Nicolas Peretto
Cardiff University
P. André
University Paris-Saclay
Pierre Bastien
Université de Montréal
David Berry
East Asian Observatory
Huei-Ru Vivien Chen
Academia Sinica
J. Di Francesco
National Research Council Canada
Chakali Eswaraiah
Chinese Academy of Sciences
Lapo Fanciullo
Academia Sinica
Laura M. Fissel
Queen's University
Jihye Hwang
Korea Astronomy and Space Science Institute
Ji-hyun Kang
Korea Astronomy and Space Science Institute
Gwanjeong Kim
National Astronomical Observatory of Japan
Kee-Tae Kim
Korea Astronomy and Space Science Institute
F. Kirchschlager
University College London (UCL)
Woojin Kwon
Seoul National University
C.W. Lee
Korea Astronomy and Space Science Institute
Hong-Li Liu
Yunnan University
A. Lyo
Korea Astronomy and Space Science Institute
Kate Pattle
National University of Ireland
Archana Soam
Universities Space Research Association
X. D. Tang
Chinese Academy of Sciences
Anthony Whitworth
Cardiff University
Tao-Chung Ching
Chinese Academy of Sciences
Simon Coudé
Universities Space Research Association
Jia-Wei Wang
Academia Sinica
D. Ward-Thompson
University of Central Lancashire
Shih-Ping Lai
Academia Sinica
Keping Qiu
Nanjing University
T. L. Bourke
SKA Organisation
Do Young Byun
Korea Astronomy and Space Science Institute
Michael Chun-Yuan Chen
University of Victoria
Zhiwei Chen
Chinese Academy of Sciences
Wen Ping Chen
National Central University
Jungyeon Cho
Chungnam National University
Yunhee Choi
Korea Astronomy and Space Science Institute
Minho Choi
Korea Astronomy and Space Science Institute
A. Chrysostomou
SKA Organisation
Eun Jung Chung
Chungnam National University
Sophia Dai
Chinese Academy of Sciences
Pham Ngoc Diep
Vietnam Academy of Science and Technology
Hao-Yuan Duan
National Tsing Hua University
Yan Duan
Chinese Academy of Sciences
D. J. Eden
Liverpool John Moores University
J. Fiege
University of Manitoba
Erica Franzmann
University of Manitoba
P. Friberg
East Asian Observatory
G. A. Fuller
University of Manchester
T. Gledhill
University of Hertfordshire
Sarah F. Graves
East Asian Observatory
J. S. Greaves
Cardiff University
Matt Griffin
Cardiff University
Qilao Gu
Chinese University of Hong Kong
Ilseung Han
Korea Astronomy and Space Science Institute
J. Hatchell
University of Exeter
S. Hayashi
National Astronomical Observatory of Japan
Il-Gyo Jeong
Korea Astronomy and Space Science Institute
Miju Kang
Korea Astronomy and Space Science Institute
Sung-Ju Kang
Korea Astronomy and Space Science Institute
Akimasa Kataoka
National Astronomical Observatory of Japan
K. Kawabata
Hiroshima University
F. Kemper
Academia Sinica
Mi-Ryang Kim
Korea Astronomy and Space Science Institute
Kyoung Hee Kim
Korea Astronomy and Space Science Institute
Jongsoo Kim
Korea Astronomy and Space Science Institute
Shinyoung Kim
Korea Astronomy and Space Science Institute
J. Kirk
University of Central Lancashire
Masato I. N. Kobayashi
Tohoku University
Vera Konyves
University of Central Lancashire
Takayoshi Kusune
National Astronomical Observatory of Japan
Jungmi Kwon
University of Tokyo
Kevin Lacaille
McMaster University
Chi Yan Law
Astronomy and plasmaphysics 2
Chinese University of Hong Kong
Chin-Fei Lee
Academia Sinica
Yong-Hee Lee
East Asian Observatory
Sang Sung Lee
Korea Astronomy and Space Science Institute
H. Lee
Chungnam National University
Jeong Eun Lee
Kyung Hee University
Hua-Bai Li
Chinese University of Hong Kong
D. Li
Chinese Academy of Sciences
Dalei Li
Chinese Academy of Sciences
J. Liu
Nanjing University
Tie Liu
Chinese Academy of Sciences
Sheng-Yuan Liu
Academia Sinica
X. Lu
National Astronomical Observatory of Japan
Steve Mairs
East Asian Observatory
Masafumi Matsumura
Kagawa University
B. C. Matthews
National Research Council Canada
Gerald H. Moriarty-Schieven
National Research Council Canada
Tetsuya Nagata
Kyoto University
Fumitaka Nakamura
National Astronomical Observatory of Japan
Hiroyuki Nakanishi
Kagoshima University
Nguyen Bich Ngoc
Vietnam Academy of Science and Technology
Nagayoshi Ohashi
National Astronomical Observatory of Japan
G. Park
Korea Astronomy and Space Science Institute
Harriet Parsons
East Asian Observatory
Tae-Soo Pyo
National Astronomical Observatory of Japan
Lei Qian
Chinese Academy of Sciences
R. Rao
Academia Sinica
J. M.C. Rawlings
University College London (UCL)
M.G. Rawlings
East Asian Observatory
Brendan Retter
Cardiff University
J. Richer
University of Cambridge
Andrew Rigby
Cardiff University
Hiro Saito
University of Tsukuba
G. Savini
University College London (UCL)
A. M. M. Scaife
University of Manchester
Masumichi Seta
Kwansei Gakuin University
H. Shinnaga
Kagoshima University
Motohide Tamura
National Astronomical Observatory of Japan
Ya-Wen Tang
Academia Sinica
Kohji Tomisaka
National Astronomical Observatory of Japan
Le Ngoc Tram
Vietnam Academy of Science and Technology
Yusuke Tsukamoto
Kagoshima University
Serena Viti
University College London (UCL)
Hongchi Wang
Chinese Academy of Sciences
Jinjin Xie
Chinese Academy of Sciences
Hsi-Wei Yen
Academia Sinica
Hyunju Yoo
Korea Astronomy and Space Science Institute
Jinghua Yuan
Chinese Academy of Sciences
Hyeong-Sik Yun
Kyung Hee University
Tetsuya Zenko
Kyoto University
Guoyin Zhang
Chinese Academy of Sciences
Chuan-Peng Zhang
Chinese Academy of Sciences
Yapeng Zhang
Chinese University of Hong Kong
Jianjun Zhou
Chinese Academy of Sciences
Lei Zhu
Chinese Academy of Sciences
I. De Looze
University College London (UCL)
C. D. Dowell
Jet Propulsion Laboratory, California Institute of Technology
S. Eyres
University of South Wales
R. Friesen
National Radio Astronomy Observatory
Jean-François Robitaille
Grenoble Alpes University
Sven Van Loo
University of Leeds
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 647 A78Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
Other Physics Topics
Fusion, Plasma and Space Physics
DOI
10.1051/0004-6361/202038624